A number of masonry laying aids have been proposed. While each offers certain advantages, each has significant drawbacks.
U.S. Pat. No. 4,689,931 to Hodges discloses a masonry laying device comprising a pair of sawtooth-shaped arm members held in parallel by a bridge member. The devices are laid between courses of masonry elements with the upper and lower parts of the sawtooths contacting the elements of the upper and lower courses, respectively. The sawtooth permits the devices to be overlaid at different angles and in different, intersecting planes. However, the sawtooth provides openings through which the mortar can pass when being struck by the mason, preventing good compression of the mortar for strengthening the resulting mortar joint.
U.S. Pat. No. 4,136,498 to Kanigan describes another device including a lattice or web of vertical walls having a height equal to a desired height between courses of masonry elements and additionally provided with upper and lower projecting conical members supported on the webs. The conical members are intended to be received in the vertical apertures provided in certain types of bricks and blocks. A major disadvantage is the inability to use the device equally with blocks or bricks lacking vertical apertures as well as those having such apertures.
U.S. Pat. No. 3,183,628 to Smith discloses a Continuous, masonry wall reinforcing device including a pair of elongated parallel members held together by one or more intermediate coupling members. Unlike the devices of the previous two patents, this device is intended to provide only reinforcement and not course leveling capability. Accordingly, it is less versatile than either of the two devices first discussed.
U.S. Pat. No. 4,095,384 to Zarriello describes the use of cardboard block spacers. Notwithstanding the partial tar coating, such spacers are subject to rot and weakening of the resulting joint. Moreover, the cardboard appears to provide less reinforcing strength than would metal or even plastic devices.
U.S. Pat. Nos. 4,277,927 to Richter, 3,501,877 to White, 3,426,497 to Mundy and 3,196,581 to Castelli all describe individual spacers for positioning between individual masonry elements. One major disadvantage of such individual elements is that they do not provide the reinforcing strength that longer, continuous elements would provide. A second disadvantage is that any leveling errors are more likely to be propagated through the wall. Longer, continuous elements tend to smooth and dampen any leveling irregularities.